Synthesis of 4-bromo- and 6-bromoindoles and of 4-amino- and 6-aminoindoles and reactions of these compounds was written by Plieninger, Hans;Suehiro, T.;Suhr, K.;Decker, M.. And the article was included in Chemische Berichte in 1955.Synthetic Route of C9H6BrNO2 This article mentions the following:
Bromination of o-O2NC6H4Me gives a mixture of 4,2- and 6,2-Br(O2N)C6H3Me which with (CO2Et)2 in the presence of NaOEt yields a mixture of the Na salts of 4,2- (I) and 6,2-Br(O2N)C6H3COCO2H (II); on cooling the aqueous solution, the less soluble salt of I separates first, and with HCl gives I, m. 138-40°; the acidified mother liquor yields II, m. 117°. I and II can be reduced with Fe(OH)2 to 4-bromo-2-carboxyindole (III), m. 263°, and the 6-Br isomer (IV), m. 220-4°, resp. Refluxed with Cu2Br2 and quinoline, these acids are decarboxylated to 4- and 6-bromoindoles, yellow oil and solid m. 94°, resp.; refluxing with Cu2Cl2 gives 4-and 6-chloroindoles, colorless oil, and solid m. 78-80°, resp. Refluxing III with a 15% solution of HCl in EtOH gives the Et ester, m. 161°; Et ester of IV, m. 186-7°. The Et ester of III with piperidine and 30% aqueous formalin in the presence of 60% aqueous AcOH produces 3-piperidinomethyl-4-bromo-2-carbethoxyindole (V), m. 148°; similarly, the Et ester of IV yields the 6-Br isomer (VI), m. 122-4°. 4-Bromoindole (VII), with pyridine, 30% aqueous formalin, and 60% aqueous AcOH yields 3-piperidinomethyl-4-bromoindole (VIII), m. 190°, on cooling, and methylation with Me2SO4 in EtOH and treatment with 1-carbethoxy-2-cyclohexanone and Na-OEt produces 1-(4-bromo-α-skatyl)-1-carbethoxy-2-cyclohexanone (IX), m. 160-5°. V similarly gives 1-(2-carbethoxy-4-bromo-α-skatyl)-1-carbethoxy-2-cyclohexanone (X), m. 201°, and VI gives the 6-bromo-α-skatyl isomer, m. 194-6°. VIII with BzOH, Me2SO4, and 1-carbobenzyloxy-2-cyclohexanone in the presence of BzOK gives 1-(4-bromo-α-skatyl)-1-carbobenzyloxy-2-cyclohexanone (XI), m. 116-17°. Attempts to cyclize IX in the presence of Mg in THF, Na in xylene, or Na in liquid NH3, and to cyclize X in the presence of Na or Li under various conditions all failed. 1-Benzyl-4-bromoindole with MeMgI and solid CO2 yields a complex which can be destroyed to give 1-benzyl-4-carboxyindole, m. 178-80°. III with concentrated NH4OH gives 4-aminoindole, m. 108°; similarly IV yields 6-aminoindole, m. 68-70°, forming with Ac2O and pyridine the N-Ac derivative, m. 169°. In the experiment, the researchers used many compounds, for example, 4-Bromo-1H-indole-2-carboxylic acid (cas: 16732-64-2Synthetic Route of C9H6BrNO2).
4-Bromo-1H-indole-2-carboxylic acid (cas: 16732-64-2) belongs to indole derivatives. Indole produced by Proteus, Pseudomonas, Escherichia and other species was shown to be a growth promoting factor in Arabidopsis thaliana. It is used in perfumery and in making tryptophan, an essential amino acid, and indoleacetic acid (heteroauxin), a hormone that promotes the development of roots in plant cuttings.Synthetic Route of C9H6BrNO2
Referemce:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles